SciDAVis - Improvements SVN-temp

Implemented feature request #002305: Inserting like in Origin.

- minor fix in TableModel

- improved copy routines for double and datetime columns
- fixed flags() in ReadOnlyTableModel
- added missing reading functions in AbstractDateTimeDataSource
that got lost when merging Knut's changes
- fixed all compiling errors of filtertest

- merged my changes with Knut's
- modified the test program to work with the current
TableModel, TableView and the data sources
Status of the test program: It works so far, but
only with string columns

- Data sources are now type safe, that is, there's no implicit conversion
between double, QString and QDateTime any more. This means you have to
cast AbstractDataSource to its subclasses before you can read the actual
data.
- Added conversion filters DateTime2Double, DateTime2String, Double2DateTime
and String2DateTime based on the prior code for implicit conversion.
Filters for month and day based conversion yet to do. Need to investigate
two failing unit tests.
- Added automatic type conversion to ReadOnlyTableModel.
- Fixed some bits in TableModel.
- Filter test program demonstrates a basically working edit->filter->display
chain; some things still need to be fixed, though.
- Some small improvements to filters and their documentation.

- committing the current version of TableModel
(not tested and still lacking some functionality)

- Implemented the possibility to specify the decimal separators when importing ASCII files.

- Dropped default value for template argument of Interval to enforce readable code.
- Simplified implementation of Interval a bit.
- Added some unit tests (based on CppUnit, http://cppunit.sourceforge.net).

- replaced "Interval<>" by "Interval<int>" to
increase code readablilty

- fixed some compiling errors in filtertest
- improved code readability a little bit